The invention relates generally to buckles, and more particularly to a side release buckle having improved distribution of stress under loads.
It is well-known in the prior art to provide a plastic buckle with a side release feature effected by pressing the side portions of the buckle. Such buckles are used in toolbelts, life preservers, harnesses, seatbelts, scuba equipment and similar apparatus. An example of such a buckle is disclosed in U.S. Pat. No. 5,222,279 to Frano et al. wherein the protuberances on the arms of the male member are depressed to release the buckle. Another example of this type of buckle is illustrated in FIGS. 1-3.
As shown in FIGS. 1-3, the buckle 10 consists of a female member 12 and male member 14. The female member 12 includes an open cavity 13 disposed therein and apertures 16, 18 formed in opposite side walls thereof. Male member 14 includes a base 20 and two resilient spring arms 22, 24 extending therefrom, each having a protuberance 26, 28 on its free end. The protuberances 26, 28 are urged into the open cavity 13 and the resilient arms 22, 24 flex inwardly as the male member 14 is inserted into the female member 6. When the male member 14 reaches its final position within the female member 16, i.e., in a locked state, the flexible arms 22, 24 flex outwardly and the protuberances 6, 28 align with and protrude from the respective apertures 16, 18.
Note that near the junction between the base 20 and the arms 22, 24 there is a collar or shoulder 30 that spans around the perimeter of the base 20 of the male member 20. The shoulder 30 interfaces with the surface of mouth 15 which defines the opening 13 to the cavity in the female member 12. In some other buckles of the prior art the shoulder of the male member may not be continuous. However, these buckles functions similarly. In other buckles of the prior art the surface of the mouth may not even interface with the male member when the buckle is in a locked state.
Under normal conditions, buckle 10 may experience stress from straight and/or torsional loads caused by the movement of the webs. The straight load is a linear force and the torsional load is a twisting force applied to the members 12, 14. Such torsional forces are illustrated in FIG. 3 as arrows A, B. Because of the construction of the prior art buckles described above, such torsional forces are exerted only on the male member 14 and cause it to bend along its length, thereby adding stress to the pre-existing stress exerted on the arms by the straight loads.
Under the additional stress, the surface of the protuberances 26, 28 may unseat from the apertures 16, 18 in the female member 12, and thus only part of the catch area of the male member 14 may interface with the female member 12 when the male and female members 12, 14 are aligned and locked. Consequently, the male member 14 may disengage from the female member 12. In addition, one of the arms 22, 24 may break under the additional stress. In this condition, the male member 14 will certainly disengage from the female member 12.
It would be therefore desirable to provide a buckle that would reduce the stress forces on the arms described above by distributing them to another portion of the buckle better suited to handle such stresses.